The processing of oxide dispersion strengthened (ODS) steels involves ball milling, where the oxide forming species are driven in solid solution. Precipitation of the nanometre-scale oxides occurs during subsequent annealing and consolidation. This paper reports in-situ Small-Angle X-ray Scattering measurements of the formation of these precipitates during heating of cold-compressed as-milled powders. Clusters are already initially present, and precipitation starts at 300 degrees C. The maximum precipitate density is achieved at 600 degrees C, followed by very slow coarsening at higher temperature. These results open the way to understand the coupled evolution of precipitation and crystalline defects during heating and consolidation of ODS steels. (C) 2016 Elsevier B.V. All rights reserved.